Green transportation

New electrolysis cells pave the way for cheaper hydrogen

Ceramic electrolysis cells with new electrode material show promising durability. The cells can efficiently convert electricity into green fuels.

0,3 mm tynde keramiske elektrolyseceller med nye langtidsholdbare Ni-GDC elektroder indgår i stakke, hvor elektricitet kan spalte vand, som i form af damp sendes ind via store huller i kanten af stakkene. — Thin ceramic electrolysis cells (0.3 mm) containing new long-lasting Ni-GDC electrodes have been developed for integration in stacks where electricity can split water. The water is supplied as steam through large holes at the edge of the stacks. Photo Bax Lindhart.

Thursday 30 May 2024

Peter Aagaard Brixen

Ceramic electrolysis cells with new electrodes show good results and no signs of electrode deterioration after 1,000 hours of testing at DTU. Electrolysis cells play a key role in converting green electricity from wind turbines and solar cells into fuels such as hydrogen, methanol and ammonia that can help reduce CO₂ emissions and promote sustainable transportation and industry.

Researchers at DTU have fabricated and tested a new type of ceramic electrolysis cells with Ni-GDC fuel electrodes and demonstrated that instead of wearing out, the electrodes maintain their performance. Professor at DTU Henrik Lund Frandsen estimates that the increased lifetime of Ni-GDC electrolysis cells can lead to significant savings in material consumption in future power-to-x plants and reduce the price of green hydrogen by up to 5 %.

"If we can get ceramic electrolysis cells into power-to-x technology in enough places around the world, their efficiency means that you can save 25% of all the electricity needed to produce the same amount of green fuel and save up to about 20% of the price of hydrogen. And if we also improve the lifespan of the technology, it will result in material savings, which will mean a further price reduction of 5 %," says Henrik Lund Frandsen.

A thousand hours of testing

The experiments to evaluate the stability of the Ni-GDC electrodes were conducted by postdoc Morten Phan Klitkou and others at DTU. The tests were performed at different currents for 1000 hours. The results showed that the resistance in the fuel electrode only degraded slightly at very high current draws. The experiments showed that the primary degradation mechanism of conventional ceramic electrolysis cells could be avoided as the nickel in the electrode did not move even under the high current draw. Current cell technology would not have been able to tolerate the same strain.

However, the researchers found that there are still some challenges with the new electrolysis cells, where the new materials have caused another problem in the electrolyte. Despite this new complication, the researchers believe that the test results with the Ni-GDC electrolysis cells are very positive and show a scalable path to manufacturing highly efficient and long-lasting electrolysis cells.

Postdoc Morten Phan Klitkou shows Professor Henrik Lund Frandsen a ceramic electrode layer stretched on a plastic film. The different ceramic layers that make up the cell are glued together, after which the cells are cut into squares and fired at 1,250 degrees in a furnace. Photo: Bax Lindhardt.

Green transition

The production of hydrogen by electrolysis is a key part of the green transition, where the first step in any power-to-x, PtX process is always the production of hydrogen by electrolysis. In the future, we will have large amounts of power available from wind turbines and solar cells, including from the two energy islands to be built in the North Sea and on Bornholm. Much of the green electricity from the islands will be used to produce fuels for applications that are difficult to electrify, such as heavy road transportation, aviation, shipping, and a number of industrial processes.

Production of electrolysis cells

In Denmark, a lot of research and development of ceramic electrolysis cells has been carried out in a collaboration between the company Topsoe and researchers at DTU. In 2014, the parties entered into a non-exclusive license agreement that made it possible to manufacture and develop ceramic electrolysis cells (SOEC) in collaboration with DTU Energy. In 2023, this development led Topsoe to start construction of the world's first large scale factory to produce high-temperature electrolysis cells assembled in large numbers in so-called stacks in Herning. When the factory is completed in 2025, it will be able to produce 500 MW of electrolysis units annually, and by 2030, production will be expanded to 5 GW annually.

Henrik Lund Frandsen estimates that it will take up to ten years before the Ni-GDC electrolysis cells are fully scaled up and utilized in Power-to-X plants internationally.

Fakta

Electrolysis cells based on nickel and cerium oxide

The Ni-GDC fuel electrode and a number of other materials play crucial roles in an electrolysis cell that can produce hydrogen from water and electricity. The electrode used consists of nickel (Ni) and cerium oxide with added gadolinium (GDC). Cerium oxide is a ceramic material that can act as a transport channel for electricity and oxygen ions and, together with Ni, form a so-called electrode in these cells, where the electrical energy converts water (H₂O) into hydrogen (H₂) and oxygen (O₂).

The Ni-GDC electrode has several important functions in speeding up a chemical reaction, where the nickel catalyst on the surface of the electrode helps break down water molecules into hydrogen ions (H⁺) and oxygen ions (O²⁻), then the GDC is used to transport the oxygen ions. Once the process has produced green hydrogen, it can be stored or converted further and used as a carbon-neutral liquid fuel.

Laboratory-scale ceramic electrolysis cell before application of an oxygen electrode. For commercial use, approximately 100 larger cells are stacked to form a stack. A power-to-x plant consists of many electrolysis stacks where water is split into hydrogen and oxygen. Photo: Bax Lindhardt.

In the laboratory, the ceramic electrolysis cells are mounted in a ceramic test house to test a single cell at a time. The test housing, which is placed in an oven, supplies the cell with electricity, water vapor and various gases. Photo: Bax Lindhardt.

The finished electrolysis cells with long-lasting electrodes are tested in a test setup that mimics a production environment. An oven is used to control the temperature and the cells are supplied with hydrogen, water vapor and air. At the same time, the cell is monitored with a range of sensors and equipment for detailed characterization of the cell condition. Photo: Bax Lindhardt.

Topic

Green transportation

The transportation sector is emitting more and more CO2 from cars, trucks, planes and shipping. To reverse this trend, more of the known solutions and technologies need to come into play.

DTU is a leader in research and education in key technologies such as green electricity, green fuels, electrification of society and battery technology development.

Read more on the green transportation topic page.

Contact

Morten Phan Klitkou Postdoc Mobile: +45 22447497

Henrik Lund Frandsen Professor Mobile: +45 93511618